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Stainless Steels Containing Niobium Andrew Backhouse Outokumpu - - PowerPoint PPT Presentation
Stainless Steels Containing Niobium Andrew Backhouse Outokumpu - - PowerPoint PPT Presentation
Future Developments in Stainless Steels Containing Niobium Andrew Backhouse Outokumpu Stainless Ltd Sheffield, UK Future Developments in Stainless Steels Containing Niobium Andrew Backhouse Outokumpu Stainless Ltd Sheffield, UK Stainless
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The City of Sheffield….is understood by all as the undisputed origin for the foundation of the knowledge that ended up in the development of…steels containing niobium Tadeu Carneiro, CEO of CBMM, 2014
Harry Brearley Produced first commercial scale cast of stainless steel in Sheffield August 1913
Brown-Firth
Avesta Sheffield Firth Vickers British Steel Corporation British Steel Stainless
Outokumpu
Stainless Steels Niobium Outokumpu Sheffield
In this bright future you can’t forget your past
- Bob Marley
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Outokumpu operates around the world
Shanghai Tornio Kemi Sheffield New Castle Richburg San Luis Potosí Calvert Avesta Degerfors Nyby Wildwood Bochum Krefeld & Benrath Dahlerbrück Dillenburg
Integrated melt shop, hot and cold rolling Other mills Service center Mine To be closed
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Austenitic (CrNi) 58% Austenitic (CrNiMo) 17% Ferritic 19% Duplex 3% Other 3%
Outokumpu Stainless Steel Production
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Consumer goods & Medical 17% Automotive 9% Heavy industries 8% Other 12%
Balanced customer base across industries
Architecture, Building & Construction 10 % Chemical, petrochemical and energy 17 % Metal processing & Tubes 27%
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Austenitic 304 is all around us
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8/18/2015 8
Stainless Steel in Commercial Kitchens
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- Surface Finish and Appearance
- Uniform, consistent & smart appearance
- Low surface roughness & no crevices at joints
- Corrosion resistant
- No rust spots during use
- Resistant to foodstuffs eg acidic foods such as vinegar & salt (eg soup)
- Resistant to cleaning fluids & disinfectants, many of which contain strong
chlorine based bleaches
- Two grades predominate today in UK
- 304, 1.4301; ~18Cr, 8Ni austenitic stainless steel
- 430, 1.4016; ~17Cr ferritic stainless steel
Requirements of Stainless Steels in professional catering equipment
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Greater corrosion risks with 430 grade
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8/18/2015
Roping in 430 grade ferritic stainless steels
- Surface roughening that occurs
during cold working ( eg deep drawing) operations
- Strong directional furrows become
visible only after forming
- Caused by: Texture development in
the sub-structure - non-equiaxed & unfavourable orientation of grains
- Poor surface appearance
- Time consuming & high cost to
remove by polishing
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Roping Index indicates polishing need
- 15
- 10
- 5
5 10 15 10 20 30 40 50 60 70 80
Profile height (µm) Profile length (mm) High RI (7.5) Low RI (0.9)
- Outokumpu has developed a
Roping Index (RI) that is based
- n advanced surface profile
measurements
- A sophisticated technique for
roping intensity evaluation
- The Roping Index is used for
process development, benchmarking, customer support and quality control purposes
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Sensitization
- formation of chromium carbides; loss of
corrosion resistance in 430/1.4016 Embrittlement
- martensite formation in standard 430/1.4016
- development of very large grains {“Elephant
Grains”} in the Heat Affected Zone.
Weldability of standard ferritic stainless steels
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- Basic Concept: A new ferritic stainless steel that can be a low cost
alternative to 304L/1.4307 in “everyday” applications.
- Pitting corrosion resistance equal or slightly better than grade 304
- Good weldability of cold rolled wide sheet
- Ability to produce excellent surface finish, including deep drawn components
CORE 1.4622 Ferritic Stainless Steel
C C Cr Cr Ni Ni Ti Ti Nb Nb CORE 304L/1.4307 0.025 18 8
- CORE 1.4622
0.020 21
- 0.1 – 0.7
0.1 – 0.7
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Niobium & Titanium Stabilisation
- Acting jointly together to produce (Ti, Nb) (C, N) particles
- Help produce favourable crystallographic texture during hot rolling of
slabs
- in combination with controlled casting & hot rolling process
parameters
- Produce roping-free surfaces after forming
- Easily polished
- Prevent Sensitisation
- Retain good corrosion resistance after welding
- Control (Reduce) level of grain growth in weld HAZ
- Adequate ductility
Cube shaped particle of (Ti, Nb) (C, N) with small particles of NbC attached Cube side is 3µm (Nooning et al, 2001)
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Roping Index below 1 – Virtually roping free
Lower RI ensures less polishing is needed after deep-drawing
0.3 3.0 4.5 Core 4622 Moda 430 430 (market average)
Roping Index (RI)
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Corrosion Resistance
1.4622 1.4307 / 304L 1.4016 / 430
14 day Neutral Salt Spray test ISO 9227 (5% NaCl at 35°C) Surface Finish: Outokumpu Phoenix Brushed surfaces Salt spray testing can be used to compare performance
- f different grades
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Corrosion Resistance
1.4509/441 (18% Cr) 1.4301/304 (18%Cr, 8%Ni) 1.4622 (21% Cr)
Cyclic salt spray test, 100 hours 5% NaCl 5 min spraying, 55 min drying at 35°C, humidity 70%
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Corrosion Resistance
Pitting potential Relative values of pitting corrosion potential in 0.02M NaCl as a function of PREN
304L/ 441/ 316L/ /444 430/ 409/
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Weldability
- Pitting corrosion resistance
- f autogenous TIG weld
similar to parent metal
1.4509/441 1.4307/304L 1.4622 Relative pitting corrosion potential in 0.02M NaCl
- Stabilization prevents
precipitation of Cr carbides
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- Save money
- Stainless Steel sold on a two-part price:
Tot
- tal
al Price e = Base e price e + Al Alloy y Sur urcharge harge (Al Alloy y Adjus ustm tment ent Factor
- r)
- Average European Base
se Price: 304L 2mm thick cold rolled sheet: €1070 0 per tonne ne (Beginning of July 2015, Source: Steel First)
What is the advantage of 1.4622 ?
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Alloy Surcharges
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Alloy Surcharges
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Alloy Surcharges
Source : www.outokumpu.com
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- Save money
- Increase likelihood of selection of stainless steels over plastics & coated
mild steels
- Reduce threat from “stainless look-alike” materials
- Improved environment and more sustainable option
- Reduced use of the Earth’s nickel resources, compared to 304 grades
- Encouragement of use of stainless steel promotes sustainability of
resources:
- Long life stainless steel lasts longer than less durable alternatives
- Stainless Steel is itself 100% recyclable at end-of-life
- “New” stainless steel from Outokumpu contains 80% recycled material
What are the advantages of CORE 1.4622 ?
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Primary Raw Material for Stainless Steel Recycled Scrap
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Adag age e - defin inition ition
“a traditional opinion that is accepted by many as true or partially true”
1.
- 1. The general
ral public ic view: w:
“Stainless Steel is one type
e of material and it is
completely rust–pr
proo
- of in all circumstances”
- 2. The catering trade buyer’s view:
“Stainless Steel occurs in two forms
ms.
There is a non-ma
magn gneti tic stainless steel (the best st type that is completely rust-proof), and there is a magne netic tic type that is cheaper, not as good, and
might go slightly rusty sty over time”
Adages in stainless steel
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- Many possibilities for stabilised ferritic
stainless steels in catering equipment
- Flat panel fabrications
- Deep drawn & polished cookware
Applications
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Applications
“Light/medium weight” welded fabrications & structures Mine rescue chamber (under construction) Stainless steel for fire resistance; no paint coating required Courtesy: HEAT-IT
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Applications for 1.4622
Mine rescue chamber installed and ready for use
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- Niobium-Titanium stabilised Ferritic Stainless Steel CORE
E 1. 1.4622 4622 can be a good alternative to standard 304L in many everyday applications
- The metallurgy & processing operations are proven and understood
- There are significant cost advantages over 304L
- This helps increased use of stainless steels in general
- which leads to a more sustainable and environmental friendly world
Summary
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